1. Technical Field
The present disclosure relates to a method of manufacturing an image display device and a method of selecting a color filter.
2. Background Art
Liquid crystal display devices have been rapidly popularized in numerous areas of usage, competition on the manufacturing cost and the image quality has been intensifying every year. In all kinds of liquid crystal display devices, higher contrast, higher response speed, higher color reproduction, high luminance, and the like have been required. Among those, higher color reproductivity and higher luminance depend on the backlight light source and the color filter used in the liquid crystal display device, and simultaneous achievement of both the higher color reproductivity and higher luminance in high level compared to that of the conventional liquid crystal display devices has been in demand.
Alternative to a cold-cathode fluorescent tube which is a conventional backlight light source, an LED-type backlight light source has been known for its long operational life, high luminance, and mercury-free property. In such an LED-type backlight, blue-light emitted from an LED and yellow-light emitted from a YAG-based fluorescent material which is excited by the blue light are used for a white-light light source. However, higher color reproductivity than that obtained by such a white-light light source has been in demand.
Relating to the above, a color-image display device which employs a backlight-light source made of a combination of a blue or a deep-blue LED and a fluorescent material, and a color filter configured to block excessive wavelength in the blue-region inherent to an LED backlight has been known, which is supposed to be able to realize a color image display device with a high luminance when it is designed for a high color reproduction range, for example, see JP 2006-47975A.
Also, it has been known a color image display device which includes a solid light emitting element configured to emit light in a specific wavelength region, and a semiconductor light emitting device which include a green fluorescent material and a red fluorescent material respectively having specific emission peak. A virtual color filter is simulated based on the emission spectrum of the semiconductor light emitting device to fit in a certain range of the NTSC ratio. In a virtual color image display device having a virtual color filter which is simulated as described above, optical utilization efficiencies at two points whose NTSC ratios are in the specific region are calculated. Using the two points, the relation between the optical utilization efficiencies and the NTSC ratios are determined in a linear function, and color image display elements that satisfy the linear function are employed in a known color image display device, for example, see JP 2009-212508 A. The color image display device is said to be able to achieve wide color reproductivity as the whole of an image without impairing brightness of the image and provide easy white balance adjustment.
Also, a semiconductor light emitting device which has a semiconductor light emitting element, a green fluorescent material, and a red fluorescent material activated with Mn4+ with a narrow half value width of the emission spectrum is known, and is said to be able to realize a display configured to display a deeper red color than a conventional red color, for example, see JP 2010-93132 A.